Signaling system for single-track railways.



No. 692,915. Patented Feb. II, I902.

' W. W. SALMON.

SIGNALING SYSTEM FOR SINGLE TRACK BAILWAYS.

(Application filed July 21, 1894.)

(No Model.)

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UNITED STATES PATENT C EicE.

\VILMER \V. SALMON, OF CHICAGO,

ILLINOIS, ASSIGNOR TO THE HALL SIGNAL COMPANY, A CORPORATION OF MAINE.

SPECIFICATION forming part of Letters Patent No. 692,915, dated February 1 1, 1902.

Application filed July 21, 1894. Serial No. 518,218. (No model.)

To aZZ whom, it HMI/Z/ concern:

Be it known that LWILMER W. SALMON, a citizen of the United States, and a resident of Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in SignalingSystems forSingle- Track Railways, of which the following is a specification.

My invention relates to electric block-signaling systems for single-track roads; and it has for its object to provide a more reliable system of this nature than has been heretofore known.

It consists of the various features hereinafter pointed out.

The system herein described is a modification of an electric signaling system described in an application filed simultaneously herewith, the principal difference being that in the present system the signal operating or controlling, circuits stand normally open,with the signals at danger, while in the other system the signal-circuits are normally closed and the signals at safety. To further distin gu ish the cases, I arbitrarily designate this case Case No. 6 and the other case Case The accompanying drawing represents diagrammatically the preferred embodiment of my present invention.

In the diagram the track is provided with a series of signals A CE, 850., to signal trains running in the direction of the arrow, or outrunning trains, and a series of signals F D B, &c., to signal the trains running in the opposite direction, or inrunning trains. The signals A C E, 810., may be therefore termed outrunning signals, and the blocks which they guard outrunning blocks, the signals F D B, &c., being termed inrunning signals and their blocks inrunniug blocks. Of course the terms inrunning and outrunning could be applied to either series of signals, and the terms' are chosen and applied merely for the purposes of description. The signals are provided each with a signal-circuit for operating or controlling the signal, and these signal-circuits are controlled by the passage of a train by means of trackcircuits. There are various types of trackcircuits which might be employedin carrying out the broad spirit of myinvention-for example, track circuits permanently un broken, normally closed, ornormally broken, track-circuits operated by track instruments, or track-circuits, including the rails of the track. The track-circuits shown in the drawinginclude the rails of the track and are permanently unbroken, their magnets being shunted by the train. The track is divided into subsections each includinga magnet and battery. These subsections are lettered N O, O P, P Q, Q R, R S, S T. The batteries for their track-circuits are numbered 1, 9, 17, 25, 33, and 41, and their magnets are numbered 5, 13, 21, 29, 37, and 45, respectively. The signals are preferably arranged on opposite sides of the track, as shown. The signals on one side of the track act as danger-signals to trains advancing in one direction and as opposing signals to trains advancing in the other. Thus signals A, C, and E act as dangersignals to trains proceeding in the direction of the arrow and as opposing signals to trains proceeding in the other direction, while signals B, D, and F act as danger-signals to trains proceeding in the reverse direction to that of the arrow and opposing signals to trains proceeding in the direction of the arrow. For the sake of conciseness the terms danger-signal and opposing signal will be used in the specification with the meaning above given.

Myimproved devices will be best explained by describing in order, in connection with the drawing, the successive operations of a train upon these devices in passing over the sections of track represented. It will be understood thatin the form of my devices shown in the drawing the various signals there shown are in their normal position at danger and are put at safety by the closing of normally open signaling-circuits.

First ope-ration, on the train entering subsection N O at N in the direction ofthe arrow- As soon as the wheels strike the rails of the subsection N O the relay 5 in the rail-circuit of battery 1, Wire 2, rail 3, wire 4, relay 5, wire 6, rail 7, wire 8, back tobatteryis in the ordinary way demagnetized. The circuitmaker 4.9 thereupon drops on the contact-point of the wire 50, thus closing the former break at that point in the secondary signaling-circuit through the signal A. This circuit is as follows: signal A, wire 51 52, circuit-breaker 53 54, circuit-breaker 55 56, circuit-breaker 57 58, battery 59 60, common battery-wire 0 61, circuit-maker 49 50, back to signal A. If the circuit-breakers 53, 55, and 57 in this circuit are closed, as they will be in case there is no train upon subsections 0 P, P Q, and Q R, the closing of the break by the dropping of circuit-maker49 will close the circuit through the signal A and draw it to safety. The engineer seeing the signal A go to safety will know there is no train on the track between his own train andsignal D and will proceed. If there should at the same time be a train upon the subsection 0 P, relay 13 in the circuit of battery 9 10 ll 12, relay 13 14 15 16 will be demagnetized and circuitbreaker 53 will drop, thus making a break at that point in the-circuit through the signal A. This will prevent the circuit-maker 49 from closing thecircuit. through the signal A, and the signal A will therefore not go to safety as the first train enters the subsec tion N O, and the engineer of this train will accordingly not pass the signal A. In the same way if there be a train upon the subsection P Q as the first train enters subsection N O relay 21 in the circuit of battery l7 18 19 20, relay 21 22 23 24: will bedemagnetized and circuit-breaker 55 in the circuit through the signal A will drop and likewise prevent the closing of the break at 49 from closing the circuit through the signal A, and thus prevent that signal from going to safety. In the same way if there be a train upon subsection Q R the relay 29 in the circuit of battery 25 26 27 28, relay 29 3O 31 32 will be demaguetized. The circuit-breaker 57 also in the circuit through the signal A will drop, and thus likewise prevent the closing of that circuit at 49 from closing the circuit through the signal A. In the above-described manner the signal A will not indicate safety on the approach of a train proceeding in the direction of the arrow upon the subsectionN 0 unless the track is clear as far as the point B. When the signal A goes to safety, it makes a break at the circuit-breaker 62 in the circuit through the signal D. In my preferred form of devices the circuit-breaker 62 in the circuit of the signal D is so connected to the mechanism of the signal A that when the latter goes to safety the said circuit-breaker 62 is thereby mechanically opened, and it remains open as long as the signal A remains at safety.

Such a mechanical arrangement is well known in the art and need not be here described. The circuit through the signal D is as follows: signal D (ll 65, circuit-maker 66 67 60, battery 59 58, circuit-breaker 57 56, circuit-breaker 55 5 L, circuit-breaker 53 52 52,

ing safety, as will be hereinafter'more fully explained. The circuit-breaker 103 will also fall upon the demagnetization of relay 5, and this will cause a break at that point in the circuit through the signal B. This signal had previously been broken when the train reached the preceding subsection on the road in the same way that the circuit through the signal D was broken at 62 by the entrance of the train upon subsection N O. The fall of circuit-breaker 103 makes another break in that circuit and insures the signal B from going to safety while the train is upon subsection N O.

Second operation, on the train entering subsection 0 P.Relay 13 will be demagnetizedand circuit-breaker 53 will drop, causing a break at that point in the circuit through the signal A. The signal A will therefore not go to safety on the approach of another train upon the subsection N 0, but will indicate danger, thereby protecting the rear of the train on the subsection 0 P. The fall of the circuit-breaker 53 also makes a break at that point in the circuit through the signal D. The signal D, therefore, will not indicate safety so long as the train is upon the subsection O'P. The circuit-breaker 101 will also fall, thereby making a break at that point in the circuit through the signal preceding the signal A on the same side of the track in a manner presently to be described, thereby preventing that signal from indicating safety upon the approach of a train from the rear. The circuit-breaker 101 is also in the circuit of the signal 13, and its fall will cause another break at that point in the said circuit and prevent the signal 13 from indicating safety as long as the train is upon the subsection 0 P. The effect,therefore,of the pres ence of a train upon the subsection 0 P is to prevent signals A, B, and D from indicating y Third operation, on the entrance of the train upon the subsect'ionP Q.Circuit-makers 6S and 95 close at once, and circuit-breaker 55 opens. 68 in dropping closes the circuit through the signal 0 at that point. cuit is as follows: signal 0 70 71, circuitbreaker 72 73, circuit-breaker 74 75, circuitbreaker 76 77, battery 78 79, common battery-wire 0 SO, circuit-maker 68 69, back to signal 0. If circuit-breakers 72, 74:, and 76 are closed, as they will be if there is no train upon subsections Q R, R S, or S T, the dropping of circuit-maker 68 will close the circuit through the signal C and send said signal to safety. If, however, there be a train upon the subsection Q B, it will demagnetize relay 29 and break the circuit at 72 and prevent the signal 0 from indicating safety. .In the same way if there be a train upon subsection R S relay 37 in the circuit of battery 33 34: 35 36 relay 37 38 39 40 will be demagnetized and circuit-breaker 74 will fall, thus breaking the circuit atthat point and preventing signal 0 from indicating danger. Likewise if there be a train upon subsection This cir-' S T relay 45 in circuit of battery 41 a2 4:3 44 relay 45 46 47 48 will be demagnetized and circuit-breaker 76 will drop, thus breaking the circuit at that point and. preventing sig nal Cfrom indicating danger. If, however, there be no train upon the track between Q and T, signal 0 will indicate safety as the train enters and remains upon subsection P Q, and the engineer seeing the signal 0 go to safety will know that the track is clear to the point T and will proceed past the signal 0. the circuit through signal A in the manner above described and will prevent that signal from going to safety upon the entrance of another-train on the subsection NO. The fall of this circuit-breaker 55 will also break the circuit of the signal D at that point in the manner above described and prevent that signal from indicating safety solong as the train is upon subsection P Q. As the signal 0 goes to safety it mechanically opens circuit-breaker 81 in the circuit of signal F and prevents the latter signal from indicating safety. The circuit through F is not all shown in the drawing, but is precisely like that through signal D. The effect of the presence of the train upon subsection PQ is to send the signal 0 to safety, provided the track is clear from Q to T, and to prevent signalsA and D and Ffrom going to safety upon the approach of another train.

Fourth operation, on train entering subsection QR.Relay 29 will be demagnetized, and circuit-breakers 57 and 72 will drop. dropping will cause a new break in the circuits through the signals A and D, thereby preventing each of those signals from indicating safety on the approach of another train. The fall of circuit-breaker 72 will cause a break at that point in the circuit through the signal 0 and prevent that signal from indicating safety on the approach of another train upon the subsection P Q. This circuit breaker 72 is also in the circuit through the signal F in the same way that signal-breaker 53 is in the circuit of the signal D. The fall of 72 will therefore break the circuit through the signal F at that point and will prevent the signal F from indicating safety on the approach of'a train in the reverse direction to that of the arrowclosing of circuit-maker Sat closes the circuitthrough the signal E at that point, and if the other circuit-breakers in the circuit of this signal are all closed will send thesignal-E to The circuit-breaker 55 in falling will open neer will not pass that point. circuit-breaker 74 will prevent signals 0 and F from going to safety.

safety in the same way as the closing of circuit-breaker 49 sends the signal A to safety if the circuit-breakers 53, 55, and 57 in the circuit of signal A are all closed. All of the corresponding circuit-breakers in the circuit of the signal E will be closed, provided there is no train upon the three following sections beginning with S T. The efiect of the presence of the train upon the subsection R S is accordingly to continue signals 0 and F at danger and send signal E to safety, provided there be no train upon the next three succeeding subsections.

Sixth operation, on. train entering subsection 8 T.The circuit-breakers 76 and 88 will fall, the circuit-breaker 76 thereby opening the circuit of signals 0 and F and continuing them at danger and circuit-breaker 88 opening the circuit of the signals E andthe next signal succeeding F on the same side of the track in the manner already described.

The effect of the passage of a train over the various track-sections in the direction reverse to that indicated by the arrow will be the same on the various circuits and signals as that previously described, except that it will be in the reverse order. Such a train entering upon the subsections T Swill break the circuits through the signals 0 and F at circuit-breaker 76 and continue these signals at danger or prevent their passage to safety and will break the circuit through the signal E atcircuit-breaker 8S, continuing that signal at danger.

Upon entering the sub section S R this train will close the break at .66 through the signal-circuit D, and that signal will go to safety, provided there be no train onthe subsection Q R to break the circuit at 57, or upon subsection P Q to break it at 55, or upon subsection 0 P to break it at 53, or upon subsection N O to passage of the train farther on the subsections R Q, Q P, and so on will be 'merely a duplication of that above described on T S and S R.

The effect of the The fall of the The number of blocks or subsections and of signals and circuits can of course be increased indefinitely, the arrangement of the same being mere duplications of thedevices opened by the relay 5 when it is demagnetized, so that the presence of a train upon the subsection N 0 would prevent signal D from going to safety. I prefer, however, the arrangement shown in the drawing as being of a simpler construction.

It will be noted from the above description that for an inrunning train the signal F guards its rear from the point T to the point P, that the signal D guards its rear from the pointR to the point N, and that the signal B guards its rear from the point P to a point beyond the point N. These inrunning blocks, therefore, overlap each other. In the same way it will be observed that the outrunning blocks overlap each other. It will be noted, moreover, that when an outrunning train reaches the'point N in advance of the outrunning signal A it-puts it to dangerand also puts the inrunning signal D ahead of the train to or holds it at danger, and when the train reaches the point 0 substantially at the signal Ait holds the signal to danger behind the train. The signals A and D maybe termed corresponding signals; likewise the signals 0 and F. The signals A, O, and E face the outrunning trains, or opposite the direction of the arrow, and the signals B, D, and F face the other direction. Any point away from a signal in the direction which it faces may be said to be in advance of or to precede the signal. Points on the other side of the signal would then be said to be in the rearof or to succeed the signal. For example, the point Q With respect to the signals A, C, and E is in the rear of or succeeds the signal A, but is in advance of or precedes the signal E. With respect to the signals B, D, and F the point Q precedes or is in advance of the signal B, but is in the rear of orsucceeds the signal D.

My improved device furnishes a simple and elficient means for effectually protecting trains upon a single-track railroad both from collisions in thefront and in the rear, and as the signaling-circuits are normally open considerable saving is made in battery-power.

While I prefer to arrange the two sets of signals in the alternate manner shown in the drawing, myimproved device can still be operatively used, as will be apparent on inspection to any one skilled in the art, even if the corresponding'signals of the series be set opposite or alongside each other. Other modifications which will readily suggest themselves to any one skilled in the art may be made without departing from the spirit of my invention.

What I claim, and desire to secure by Letters Patent, is-

1. In a signaling system for single-track railways, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for the blocks normally at danger but operating to go to safety in front of the trains which they face, each outrunning signal guarding a portion of the track which is also guarded by a corresponding inrunning signal, said. inrunning signal being located in the rear of its corresponding outrunning signal not less than the distance between the said inrunning signal and the next inrunning signal toward the said outrunning signal, means for operating the in.- running signal to'put it to or hold it at danger controlled by an outrunning train from a point in advance of said corresponding outrunning signal and means for operating the outrunning signal to put it to danger controlled by an outrunningtrain from a point substantially at the said outrunning signal, substantially as-set forth.

2. In a signaling system. for single-track railways, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for theblocks normally at danger but operating to go to safety in front of the trains which they face, each outrunning signal guarding a portion of the track which is also guarded bya corresponding inrunning signal, said inrunning signal beinglocated in the rear of its corresponding outrunning signal not less than the distance between the said inrunning signal and the next inrunning signal toward the said out running signal, means for operating the inrunning signal to put it toor hold it at danger controlled by an outrunning train from a point in advance of said corresponding outrunning signal, means for operating said inrunning signal to put it to danger controlled by an inrunning train from a point substam tially at the inrunning signal, and means for operating the outrunning signal to put it to danger controlled by an outrunning train from a point substantially at the said outrunning signal and by an inrunning train to hold it at or put it to danger from a point in the rear of said outrunning signal and not nearer thereto than the corresponding inrunning signal, substantially as set forth.

3. In an electric signaling system for singletrack railways, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for the blocks nor-v mally at dangerbut operating to go to safety in front of the trains which they face and normally denergized operatingor controlling circuits for the signals, each outrunning signal guarding a portion of the track which is also guarded by a corresponding inrunning signal, said inrunning signal being located in the rear of its corresponding outrunning signal not less than the distance between the said inrunning signal and the next inrunning the said outrunning signal, substantially as set forth. 7 i v 4. In an electric signaling system for singletrack railways, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for the blocks normally at danger but operating to go to safety in front of the trains which they face and normally deenergized operating or controlling circuits for the signals, each outrunning signal guarding a portion of the track which is also guarded by a corresponding inrunning signal, said inrunning signal being located in the rear of its corresponding outrunniug signal not less than the distance between the said inrunning signal and the next in running signal toward the said outrunni'ng signal, a track-circuit for operating the circuit for' the inrunning signal to put it toor hold it at danger controlled by an outrunning train from a point in advance of said correspond ing outrunning signal, a track-circuit for operating the circuit for the inrunning signal to put it to danger controlled by an inrunning train from a point substantially at-the' inrunning signal, and track-circuits for operating the circuit for the out-running signal to put it to danger controlled by an outrunning train from a point substantially at the said outrunning signal and by an inrunning train to hold it at or put it to danger from a point in the rear of said outrunning signal and not nearer thereto than the corresponding inrunning signal, substantially as set forth.

5. In an electric signaling system for sin gletrack railways, the combination of a series of outrunning blocks and a series of overlapping inrnnning blocks, signals for the blocks normally at danger but operating to go to safety in front of the trains which they face and normally deenergized operating or controlling circuits for the signals, each outrunning signal guarding a portion of the track which is also guarded by a correspondinginrunning signal, said inrunning signal being located in the rear of its corresponding outrunning signal not less than the-distance between the said inrunning signal and the next inrunning signal toward the said outrunning signal, a rail-circuit for operating the circuit for the inrunning signal to put it to or hold it at danger controlled by an outrunning train from a point in advance of said corresponding outrunning signal, a rail-circuit for operating the circuit for the inrunning signal to put it to danger controlled by an inrunning train from a point substantially at the inrunning signal, and rail-circuits for operatingthe circuit for the outrunning signal to put it,to danger controlled by an outrunning train from a point substantially at the said outrunning signal and by an inrunning train to put itto or hold it at danger from a point in the rear of said outrunning signaland not nearer thereto than the corresponding inrun ning signal, substantially as set forth.

.while'on the portion of track in advance of a signal, said signaling-circuits for operating each signal of one series beingalso controlled by the train while on any portion of the track between said signal of the first series and'the opposing signal of the other series which is the second one of said series beyond a preliminary track-section lying immediately in advance of the said signal of the first series, and the circuit for operating each signal of the second-series being controlled by the train while on any portion of the track between said signal and the farther end of a preliminary track-section lying immediately 'beyond the signal of the'tirst series which is next beyond or opposite to the next signal of the second series, substantially as set forth.

7.- In a single-track block-signalingsystem, two series of signals, eachv series adapted to act as danger-signals for trains moving in one direction and as opposing signals for trains moving in the other direction, said signals being arranged alternately along the track, first a signal from one series, then a signal from the other, and so on, electric signaling-circuits, one for each signal, normally broken at one point, controlled by the train for operating said signals, a circuit-maker in each of said circuits adapted to be closed by the train While on the section of the track immediately in advance of the signal operated by said circuit, the circuit for operating each signal of one series being also controlled by the train while on any portion of the track between said signal of the first series and the opposing signal of the other series which is the second one of said series beyond a preliminary traclcsection lying immediately in advance ofthe said signal of the first series,-

and the circuit for operating each signal of the second series being controlled by the train while on any portion of the track between said signal and theend of a preliminary tracksection lying immediately in advance of the signal of the first series'which is next beyond or opposite to the'next signal of the second series, substantially as set forth.

8. In a single-track block-signaling system, two series of signals, each series adapted to act as dangeusignalsfor trains moving in'one direction and as opposing signals for trains moving in the other direction, said signals being, arranged alternately along the track,

first a signal from one series, then a signal from the other, and so on, insulated sections of track, a track-circuit for each of said 'sections of track adapted to be operated by the train while'on said section, a relay in each of use said circuits, a secondary signaling-circuit,

normally broken at one point, adapted to opcrate each signal, a circuitmaker at said break in each signaling-circuit adapted tobe closed by the train while on the section of track in advance of the signal in said circuit, circuit-breakers in each of said signaling-circuits adapted in the signal-circuits of one series of said signals to be operated by the relays in three of said track-circuits and in the signaling-circuits of the other series'of signals to be operated by the relays in four of said track-circuits, substantially as set forth.

9. In a single-track block-signaling system, two series of signals, each series adaptedto act as danger-signals to trains moving in one direction and as opposing signals to trains moving in the other direction, said signals being arranged alternately along the track, first a signal from one series, then a signal from the other and so on, insulated sect-ions of track, a normally closed track-circuit for each of said sections of track adapted to be operated by the train while on the said section, a relay in each of said circuits, a sec-- ondary signaling-circuit, normallybroken at one point, adapted to operate each signal, a circuit-maker in each of said signaling-circuits adapted to be closed by the train while on the section of track immediately in advance of the signal of said circuit, circuitbreakers in each of said signaling-circuits, adapted in the signaling-circuits of one series of said signals to be operated by the relays in three of said track-circuits, and in the signaling-circuits of the other series to be operated by the relays of said track-circuits, substantially as set forth. &

10. In avsingle-track block-signaling sys-' tem, two series of signals, each series adapted to act as danger-signals for trains moving in one direction and as opposing signals to trains moving in the other direction, insulated sections of track, track-circuits, including the said insulated sections, adapted to be operated by the train, relays in said circuits, a secondary signaling-circuit, normally broken at one point, adapted to operate each signal, a circuit-maker at the break in each of said circuits adapted to be closed when the train is onthe section of track immediately in advance of the signal of said circuit, circuitbreakers in each of said signaling-circuits adapted in the signaling-circuits of one series of said signals to be operated by the relays of the track-circuits covering the portions of track between a signal of said first series and the opposing signal of the other series which is the second one oi said series beyond a preliminary track-section which lies immediately in advance of the said signal of the first series, and adapted in the signaling-circuits of the other series of said signals to be operated by the relays of the track-circuits covering the said preliminar track-sections and the track-sections between it and the second signal of the said other series beyond said preliminary track-section, substantially as set forth. V

11. In a single-track block-signaling system two series of signals, eachseries adapted to act as danger-signals fortrains moving in one direction and as opposing signals for trains moving in the other direction, insulated sections of track, track-circuits, normally closed, including said insulatcdsections and adapted to be operated by the train while on said sections, relays in said circuits, a secondary signaling-circuit normally broken at one point adapted to operate each signal, a circuitmaker at the break in each of said circuits adapted to be closed by the train while on the section of track immediately in advance of the signal of said circuit, circuit-breakers in each of said signaling-circuitsadapted in the signaling-circuits of one series of said signals to be operated by the relays of the track-circuits covering'the sections of track between a signal of said first series and the opposing signal of the second series which is the second one of said second series beyond a preliminary track-sectionwhich lies immediately in advance of the. said signal of the first series, and adapted in the signaling-circuits of the other series of said signals to be operated by the relays of the track-circuits covering the said preliminary track-section and the track-sections between it and the second signal of the said second series beyond said preliminary track-section, substantially as set forth.

12. In an electric signaling system for single-track railways, the combination ofa rear signal normally at danger, an opposing signal normally at danger, line-circuits for the signals and normally closed rail-circuits operated by the passage of a train for controlling or operating said signals, an electromagnetically-operated switch located in one ofsaid rail-circuits, to cause the rear signal to show safety before an approaching train when the track-section guarded by the signal is clear, a circuit-breaker to cause said signal to show danger as long as the train is in said guarded track-section, and a mechanical means to prevent the opposing signal in advance of the train from showing clear until the train has passed it, substantially as set forth.

. 13. In an electric signaling system'for single track railways, the combination of a series of rear signals normally at danger, a series of corresponding opposing signals normally at danger, line-circuits for the signals and normally closed rail-circuits operated by the passage of a train for controlling or operating said signals, an electromagneticallyoperated switch located in one of said rail-circuits to cause a rear signal to show safety before an approaching train when the tracksection guarded by the said signal is clear, a circuit-breaker to cause said signal to show danger as long as the train is in said tracksection and until after it has passed beyond the next rear signal in advance of the train,

and a mechanical means for preventing the corresponding opposing signal in advance of the train from showing clear until the train has passed it, substantially as set forth.

14. In an electric signaling-system for single-track railways, the combination of arear signal normally at danger, an opposing signal normally at danger, line-circuits for the signals and normally closed rail-circuits operated. by the passage of a train for controlling or operating said signals, an electromagnetically-operated switch located in one of said rail-circuits to cause the rear signal to show safety before an approaching train when the track-section guarded by the signal is clear, a circuit-breaker to cause said signal to show danger as long as the train is in said guarded track section, and a mechanical means for preventing the opposing signal in advance of the train from showing clear until the train has passed it, said rear signals serving to control the setting or continuing of its corresponding signal as an opposing signal, substantially. as set forth.

15. In an electric signaling system for single-track railways, the combination of a series of rear signalsnormallyat danger, a series of corresponding opposing signals normally at danger, line-circuits for the signals and normally closed rail-circuits operated by the passage of a train for controlling or operating said signals, an electromagnetically-operated switch locatedin one of said rail-circuits to cause a rear signal to show safety before an approaching train when the track section guarded by said signal is clear, a circuitbrea-ker to cause said signal to. show danger as long as the train is in said track-section and until after it has passed beyond the next rear signal in advance of the train, and a mechanical means for preventing the corresponding opposing signal in advance of the train from showing clear until the train has passed it, said rear signals serving to control the set ting or continuing of its corresponding signal as an opposing signal, substantially as set forth.

16. In an electric signaling system for single-track roads, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for the blocks and operating or controlling line-circuits for the signals, each outrunning signal guarding a portion of the track which is also guarded by a corresponding inrunning signal, said inrunning signal being located in the rear of its corresponding outrunningsignal not less than the distance between the said inrunning sig nal and the next inrunning signal toward the said outrunning signal, a track-circuit for operating the circuit for the inrunning signal to put it to danger controlled by an outrunning train and located in advance of said corresponding outrunning signal, and a trackcircuit for operating the circuit for the outrunning signal to put it to danger controlled by an outrunning train and located substana corresponding inrunning signal, said inrunv ning signal being located in the rear of its corresponding outrunning signal notless than the distance between the said inrunning signal and the next inrunning signal toward the said outrunning signal, a track-circuit for operating the circuit for the inrunning signal to put it to danger controlled by an outrunning train and located in advance of said corresponding outrunnin g signal, a track-circuit operating the circuit for the inrunnin g signal to put it to danger controlled by an inrunning train and located substantially at the inrunning signal, a track-circuit for operating the circuit for the outrunning signal to put it to danger controlled by an outrunning train and located substantially at the said outrunning signal, and a track-circuit for operating the circuit for the outrunning signal to put it to danger controlled by aninrunning train and located in the rear of said outrunning signal and not nearer thereto than the corresponding inrunning signal, the several circuits of the blocks being so arranged that the inrunning signals are connected together and the outrunning signals are connected together and the inrunning and outrunning signals are interconnected, substantially as set forth.

18. In an electric signaling system for sin- ICC gle-track roads, the combination of a series of outrunning blocks and a series of overlapping inrunning blocks, signals for the blocks and operating or controlling line-circuits for the signals, each outrunning signal guarding a portion of the track which is also guarded by a corresponding inrunning signal, said inrunning signal being located in the rear of its corresponding outrunning signal not less than the distance between the said outrunnin g signal and the next inrunning signal toward the said outrunning signal, a rail-circuit for operating the circuit for the inrunning signal to put it to danger controlled by an outrunning train and located in advance of said corresponding out-running signal, a rail-circuit for operating the circuit for the inrunning signal controlled by an inrunning train and located substantially at the inrunning signal, a rail-circuit for operating the circuit for the outrunning signal to put it to danger controlled by an outrunning train and located substantially at the said outrunning signal,

and a rail-circuit for Operating the circuit of name to this specification in the presence of the ontrunning signal to put it to danger contwo subscribing witnesses.

trolled by aninrunning train and located in U I the rear of said ontrunning signal and not I ILMD-R SALMON 5 nearer thereto than the corresponding im'unl/Vitnesses:

ning signal, substantially as set forth. L. THOMAS,

In testimony whereof I have signed my Jos. P. VAROHER. 

